Effect of aniline formaldehyde resin on the conjugation length and structure of doped polyaniline: Spectral studies

Abstract

Abstract A DBSA ( n ‐dodecylbenzene sulfate)‐complexed aniline formaldehyde [AF(DBSA) 1.0 ] was successfully synthesized with excess aniline (compared with formaldehyde) in the presence of n ‐dodecylbenzene sulfonic acid (HDBSA), which was complexed with aniline monomer before polymerization. The resin was carefully characterized with 1 H and 13 C NMR, electron spectroscopy for chemical analysis, and Fourier transform infrared and was demonstrated to be a polymer in which anilines were all complexed with HDBSA and became anilinium salts. A drastic decrease of the maximum absorption wavelength (ultraviolet–visible spectra) of DBSA‐doped polyaniline [PANI(DBSA) 0.5 ] was found when AF(DBSA) 1.0 was mixed, and this resulted from the reduced conjugation length. A similar effect on PANI(DBSA) 0.5 was found when free HDBSAs were mixed with PANI(DBSA) 0.5 . Visual inspection with an optical microscope revealed that PANI(DBSA) 0.5 /AF(DBSA) 1.0 gave uniform morphologies in various compositions, showing possible miscibility for this system. X‐ray diffraction patterns of PANI(DBSA) 0.5 /AF(DBSA) 1.0 showed that the layered structure of PANI(DBSA) 0.5 was still present but became shorter in the polyblend because of the presence of AF(DBSA) 1.0 . Solid‐state 13 C NMR spectra revealed that the reduced conjugation length was derived from the interaction of alkyl groups between HDBSA, complexed DBSA, and dopant DBSAs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3116–3125, 2005